Phenotypic and Molecular Characterization of Lacinutrix venerupis Isolated from Atlantic Horse Mackerel Trachurus...

The aim of the present study was to characterize two gram-negative bacterial strains that were isolated from diseased Atlantic Horse Mackerel Trachurus trachurus in 2017. Based on the results obtained from the biochemical and chemotaxonomic characterization, the isolates were identified as Lacinutrix spp. The highest similarity of the 16S rRNA gene sequences was obtained with the strain L. venerupis CECT 8573^T (99.1%), while other species showed similarities of 98% (L. jangbogonensis) and 97% (L. algicola and L. mariniflava). Molecular characterization by repetitive element (REP)-PCR and enterobacterial repetitive intergenic consensus (ERIC)-PCR, as well as proteomic characterization by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS), demonstrated heterogeneity between the strains from the Atlantic Horse Mackerel and the type strain, CECT 8573^T . The virulence of one of the isolates for Turbot Scophthalmus maximus, European Sea Bass Dicentrarchus labrax, Senegalese Sole Solea senegalensis, and Rainbow Trout Oncorhynchus mykiss was assessed under experimental conditions. No mortalities were recorded after intraperitoneal injections with high doses of bacteria (1 × 10⁹  CFU/mL). Thus, further studies are necessary to elucidate the impact of this bacterial species as a fish pathogen.